Discrete high impedance implementation on push-pull outputs

ABSTRACT

Methods and devices for communicating or interacting by a pen or a stylus with a digitizer are disclosed. An example method describes determining whether the device is to transmit a first information to the digitizer via the electrode or receive a second information from the digitizer via the electrode. An example device for use with the method includes a transmitter circuit, a receiver circuit, and an electrode. The method further includes isolating the electrode from the transmitter circuit in response to determining that the device is to receive the second information from the digitizer via the electrode.

BACKGROUND

The present implementations relate to communications or interactionsbetween a pen/stylus and a digitizer, and more particularly, totransmitting or receiving data at the pen/stylus over an electrode fromthe digitizer.

Electromagnetic pens or styluses are known in the art for use andcontrol of a digitizer. Position detection of the pen provides input toa computing device associated with the digitizer and is interpreted as auser command. Position detection is performed while the pen tip iseither touching and/or hovering over a detection surface of thedigitizer. Often, the digitizer is integrated with a display screen anda position of the pen over the screen is correlated with informationportrayed on the screen.

A digitizer may operate in a search mode or a tracking mode. Thedigitizer operates in a search mode when there is no communication orcontact with the pen, or the communication or contact with the pen islost and the digitizer is searching for a transmission signal, such as abeacon, from the pen. Once the digitizer finds the transmission signalfrom the pen, the digitizer performs a synchronization with the pen andthe digitizer transitions to a tracking mode. In the tracking mode, thedigitizer is in synchronization with the transmission signal from thepen and can receive information from the pen.

For example, in a typical pen/digitizer application, a high voltagealternate current (AC) signal is transmitted by the pen over anelectrode and detected by the digitizer. If the pen has to receive asignal from the digitizer over the same electrode, the electrode has tobe shared, and the pen may encounter some issues during the sharing ofthe electrode.

Therefore, there is a need for an improved mechanism to share anelectrode for transmitting data to a digitizer and receiving data fromthe digitizer.

SUMMARY

The following presents a simplified summary of one or more disclosedfeatures in order to provide a basic understanding of the disclosure.This summary is not an extensive overview of all contemplatedimplementations, and is intended to neither identify key or criticalelements of all implementations nor delineate the scope of any or allimplementations of the present disclosure. Its sole purpose is topresent some concepts of one or more features of the present disclosurein a simplified form as a prelude to the more detailed description thatis presented later.

One implementation relates to a method of communicating with adigitizer. The method may include determining, at a device having atransmitter circuit, a receiver circuit, and an electrode forcommunicating with the digitizer, whether the device is to transmit afirst information to the digitizer via the electrode or receive a secondinformation from the digitizer via the electrode and isolating theelectrode from the transmitter circuit in response to determining thatthe device is to receive the second information from the digitizer viathe electrode.

In another implementation, a device for communicating with a digitizermay include a pulse generator, a transmitter circuit, a receivercircuit, an electrode for communicating with the digitizer, a memory,and a processor in communication with the memory, wherein the processoris configured to determine whether the device is to transmit a firstinformation to the digitizer via the electrode or receive a secondinformation from the digitizer via the electrode; and isolate theelectrode from the transmitter circuit in response to determining thatthe device is to receive the second information from the digitizer viathe electrode.

In a further implementation, a computer-readable medium storingcomputer-executable instructions executable by a processor forcommunicating with a digitizer includes various instructions. Thecomputer-readable medium includes instructions for determining, by adevice having a transmitter circuit, a receiver circuit, and anelectrode for communicating with the digitizer, whether the device is totransmit a first information to the digitizer via the electrode orreceive a second information from the digitizer via the electrode, andfor isolating the electrode from the transmitter circuit in response todetermining that the device is to receive the second information fromthe digitizer via the electrode.

Additional advantages and novel features relating to features of thepresent disclosure will be set forth in part in the description thatfollows, and in part will become more apparent to those skilled in theart upon examination of the following or upon learning by practicethereof.

DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view of an example of a pen.

FIG. 2 is a schematic view of an example of a digitizer system for usewith the pen of FIG. 1.

FIG. 3 is a block diagram of an example pen with a transmitter circuit,a receiver circuit, and/or an electrode.

FIG. 4 illustrates an example transmitter circuit of a pen.

FIG. 5 illustrates an example transmitter circuit that is driving a lowvoltage on the electrode.

FIG. 6 illustrates an example transmitter circuit that is driving a highvoltage on the electrode.

FIG. 7 is illustrates an example transmitter circuit that is isolatedfrom the electrode.

FIG. 8 is a flowchart of an example method of the operation of a pen,including a method of communicating with the digitizer.

DETAILED DESCRIPTION

The addition of a high impedance mode to a high voltage push-pull driveris very expensive in terms of cost, power, and/or size, and adds asignificant amount of parasitic capacitance. For example, in a typicaldigital pen or stylus application, a high voltage alternating current(AC) signal is transmitted by the pen, over an electrode, to adigitizer. However, if the pen has to receive a signal from thedigitizer over same electrode, the pen has to be capable of switchingthe high voltage push-pull driver to a high impedance mode and with verylow parasitic capacitance.

The present disclosure provides a method, a device, and/or instructionsin a computer readable medium for communicating with a digitizer. Thedevice (e.g., a pen or a stylus) communicates/interacts with thedigitizer by determine whether the device to transmit information to thedigitizer or receive information from the digitizer via an electrode.The device isolates the electrode from a transmitter circuit of thedevice in response to determining that the device is to receiveinformation from the digitizer via the electrode.

Referring to FIG. 1, according to an example implementation, a pen 100(which may also be referred to as a stylus) may be an autonomousasynchronous device that can communicate or interact with the digitizer,for example, to transmit data (e.g., a first information) to thedigitizer and/or receive data (e.g., a second information) from thedigitizer, is described herein. The pen 100 can transmit pulses ofenergy that can represent beacon signals and/or commands generated bythe pen 100. For example, a transmitting unit (TX unit) 130 of the pen100 may transmit an electric signal generated by a pulse generator 124.In some cases, the pulse generator 124 generates one or more AC signalbursts providing pulsed signals (AC pulses), e.g., a train of pulses(signal bursts). For example, the AC pulses may be generated within acertain frequency range, such as but not limited to a frequency rangebetween 20-40 KHz. The AC pulses may use a frequency other than thefrequencies generally used to detect finger touch on a digitizer.Additionally, for example, the frequency of a burst signal from the pen100 may be orthogonal to the frequencies used to detect finger touch inthe sampling space or far enough away so that simultaneous userinteractions (e.g., pen and finger) may be possible. Also, in someimplementations, specific time slots for finger touch detection and pendetection may be defined to avoid interference or misidentification whenclose frequencies are used. In some cases, the pulse generator 124generates pulses over a defined time duration or pulse width. An examplepulse width may be between 1-2 milliseconds (msec), such as but notlimited to 1.28 msec. In some additional implementations, for example,the pen 100 can receive an electrical signal which may includeinformation (e.g., the second information) received and processed by areceiving unit (RX unit) 132.

The TX unit 130 can transmit data to the digitizer and/or the RX unit132 can receive data from the digitizer via an electrode 160 and/or tip140. In one example, the TX unit 130 and the RX unit 132 cantransmit/receive over a single electrode, e.g., electrode 160 or the tip140, in a time division multiplexing (TDM) manner. In another example,the TX unit 130 can transmit data over one electrode (e.g., a firstelectrode) and receive data over a different electrode (e.g., a secondelectrode). However, depending on the configuration of the pen 100 andthe digitizer, the TX unit 130 and the RX unit 132 can communicate withthe digitizer over the first electrode and the second electrode in a TDMmanner or at the same time (e.g., simultaneously).

The pen 100 may include a processor 112, a memory 114, and powered by apower source 110. The power source 110 may include one or morebatteries, e.g., alkaline or re-chargeable batteries.

In some cases, the pen 100 may include a power switch 102 for poweringtransmission of the pen 100 and one or more operational switches and/ordials 104 for receiving operation commands from a user. For instance,the switches 104 may control right click and eraser mode commands aswell as color selection when writing or drawing with the pen. In someother additional or optional implementations, a rocker switch may beused for right click or eraser operation. That is, at least one of theswitches 104 may be a rocker switch.

The pen 100 may include a tip 140 that operates as an antenna of the TXunit 130, and/or an electric dipole, and/or the tip 140 may be used totransmit/receive data to/from the digitizer. For example, the tip 140may transmit beacons for tracking the position of the pen 100 andpressure information. For example, one output of the pulse generator 124is electrically connected to the pen tip 140 (which may be constructedfrom a conductive material) while the other end is electricallyconnected to a frame 142 (which may comprise conductive material)surrounding the tip 140. The frame 142 may be integral to a housing unit144 and is grounded. An electric field, synchronized to a generatedsignal pulse, may be formed in a small gap 146 located between the tip140 and the frame 142. In some implementations, the geometric dimensionsof the gap and the consequent electric field may be relatively small sothat field source may be substantially close to the pen tip and mayprovide a concentrated signal at the tip. Further, the signalstransmitted by the pen 100 may be picked up at relatively concentratedpoints by the digitizer or other sensing surface and the position of thepen at that position may be conveyed to the digitizer. In some otheroptional implementations, the pen 100 may include a separate antenna andmay not use the tip 140 for transmitting the output signals.

The pen 100 may be a pressure sensitive pen that may transmitinformation regarding contact pressure applied to the tip 140. Forinstance, the pen 100 may include a pressure unit 12 in communicationwith the tip 140 and configured to detect contact force (or contactpressure) applied to the tip 140. In some cases, the tip 140 may befixedly connected to the pen 100, while in other cases, the tip 140 ismovably connected to the pen 100 to allow the tip 140 to translate inthe axial direction 150, e.g., along the longitudinal axis of the tip140. For example, in the movably connected cases, the tip 140 recedesinto the housing unit 144 along an axial direction 150 in response to auser pressing the tip 140 on a surface, and the tip 140 may move in adirection away from the housing unit 144 when the contact pressure isreleased, e.g., in a hovering state or non-operational state of the pen100. In some cases, during the axial movement, the tip 140 is engagedwith a resilient element 152, e.g., a spring whose properties aregenerally selected to obtain a desired relationship between the contactpressure and the axial displacement.

Pressure sensor unit 122 senses contact pressure applied to the tip 140and provides this pressure information to pulse generator 124. Thepulsate generator 124, based on the sensed contact pressure level,defines or alters a frequency of a pulse, and generates and initiatestransmission of the defined or the altered pulse. In some otheradditional or optional cases, a specific frequency band may be allocatedfor transmitting the pressure information. For example, a frequency bandof 20-45 KHz, e.g., 20-25 KHz, may be allocated for transmitting thepressure information. Additionally, output from the pressure sensor unit122 may be encoded with an encoder 126 for the pulses generated by pulsegenerator 124.

The pen 100 may include an encoder 126, such as but not limited to adigital encoder, operable to encode an operational state of the pen 100and/or identification information of the pen 100 into a pulse generatedby the pulse generator 124. The operational state of the pen 100 may beobtained from switch state of the switches 102, and/or the pressurestate of the pen 100 may be encoded with the encoder 126. One or moreencoding methods (e.g., Amplitude Shift Keying (ASK), Phase Shift Keying(PSK), Frequency Shift Keying (FSK), etc.) may be used to encodeinformation with the encoder 126. The encoded information from the penmay be transmitted over a plurality of transmission cycles. Forinstance, in some implementations, one bit of encoded information may betransmitted per transmission cycle. In some other implementations, thepulse generator 124, the encoder 126, the pressure sensor unit 122,and/or their functionality may be embedded in an ASIC unit 120. Inaddition, the pen 100 may include a decoder 166, such as but not limitedto a digital decoder, operable to decode a digital stream from the RXunit 132 into the second information, and pass on the second informationto the processor 112 for processing.

In some cases, a time between pulses may match a refresh cycle of adigitizer or an integer multiple of a refresh cycle of a digitizer,e.g., twice a refresh cycle of a digitizer and/or three or four times arefresh frequency of a digitizer. Alternatively or in addition, a timebetween pulses (or bursts) may be variable and may be controllablyaltered based on an operational state of the digitizer. For instance, inan implementation, the time between pulses at the pen 100 may beconfigured for 15 msec.

Referring to FIG. 2, according to an example implementation, a digitizersystem or digitizer 200 may be used with any computing device to enablecommunications/interactions between a user and a device, e.g., personalcomputers (PCs), tablets, pen enabled lap-top computers, PDAs, mobiledevices/user equipments (UEs), etc. In some implementations, thedigitizer system 200 is part of a user interface operative to detectinputs from one or more pens 100, fingers 204, and/or conductive objects206 and/or send outputs to one or more pens 100. The digitizer 200 mayoperate in a pen search mode or a pen tracking mode. In a pen searchmode, the digitizer 200 may search for a signal from the pen 100,perform synchronization with the signal transmitted from the pen 100when the signal from the pen 100 is detected or when the pen 100 comesin contact with the digitizer 200, and/or enter the tracking mode uponsuccessful completion of the synchronization with the pen 100. Thedigitizer 200 remains in the tracking mode while the pen 100 maintainscontact with the digitizer 200 or continues to receive the signal fromthe pen 100.

The digitizer system 200 may include a sensor 212 including a patternedarrangement of conductive lines (sensor lines), which may be optionallytransparent, and which are typically overlaid on a display 202. Forexample, the sensor 212 may be a grid based sensor including horizontaland vertical lines. In some cases, a width of the conductive line mayvary over its length, e.g., the width of the conductive line may benarrower around the vicinity of junction points of the grid and widerbetween the junction points. In some cases, the conductive lines may beshaped like a diamond shape array with diamond points matched tojunction points. In some implementations, the parallel conductive linesare equally spaced straight lines, and are input to amplifiers includedin application specific integrated circuit (ASIC) 216. For example, theamplifiers may be differential amplifiers.

The ASIC 216 includes, for example, circuitry to process and sample anoutput of the sensor and generate a digital representation. The digitaloutput signal is forwarded to a digital unit 220, e.g., a digital ASICunit, for further digital processing. For instance, the digital unit 220together with the ASIC 216 may serve as a controller of the digitizersystem 200 and/or may have the functionality of a controller and/or aprocessor. In some cases, a single unit may be used, e.g., in a smallscreen with limited number of lines. In some other additional oroptional implementations, the ASIC 216 operates as a detection unit forprocessing and sampling the output of the sensor. The outcome, oncedetermined, is forwarded to a host 222, e.g., a computer device or ahost computer device, via an interface 224 for processing by theoperating system or any current application. In some other cases,control functionality may be additionally or exclusively included in thehost 222, and the ASIC 216 and the digital unit 220 may be provided as asingle ASIC. In some other optional implementations, the digital unit220 and the ASICs 216 may be mounted in a PCB 230.

The ASIC 216 may be connected to the outputs of the various conductivelines in the grid and functions to process the received signals at afirst processing stage. In some cases, instead of the printed circuitboard (PCB) 230 positioned along two sides of the sensor 212, a flexcable may be used to connect the conductive lines to the ASICs 216,e.g., positioned away from a sensing surface of the digitizer 200. Asindicated above, the ASIC 216 may include one or more arrays ofamplifiers, e.g., an array of differential amplifiers, an array ofsingle ended amplifiers, or any array of differential amplifiers, andoptionally including one grounded input to amplify the sensor's signals.In some other additional or optional implementations, the groundinginput may be selected by the ASIC 216. The ASIC 216 may optionallyinclude one or more filters to remove irrelevant frequencies.Additionally, filtering is performed prior to sampling. The signal isthen sampled by an analog-to-digital (A/D) converter, optionallyfiltered by a digital filter and forwarded to digital ASIC unit, forfurther digital processing. Alternatively, the optional filtering isfully digital or fully analog.

For instance, the digital unit 220 receives the sampled data from theASIC 216, reads the sampled data, processes it and determines and/ortracks the position of physical objects, such as the pen 100 and/or thefinger 204, touching the digitizer sensor the 212. Further, for example,the digital unit 220 is operative to decode information encoded in atransmission signal from the pen 100, e.g., pressure on tip, right-clickand/or eraser mode, color for tracing, and identification, etc.According to some implementations, hovering of an object, e.g., the pen100, the finger 204 and/or the hand, may be detected and processed bythe digital unit 220. In any case, the digital unit 220 can send acalculated position to the host 222 via an interface 224.

In some implementations, the digitizer system or digitizer 200 hasseveral channels, i.e., interfaces included within the interface 224,with the host. In an example, the interface 224 includes a pen interfacefor transmitting pen coordinates on the display screen, and a fingertouch interface for transmitting finger touch coordinates on the displayscreen. In some additional examples, a same interface of the interface224 may transmit finger touch coordinates based on both single touchdetection method and multi-touch detection method. Optionally, theinterface 224 may transmit information on detected gestures.

Further, the digital unit 220 may be operative to control operation ofone or more ASIC(s) 216. For instance, the digital unit 220 may beoperative to provide a command signal to the ASIC 216 to switch betweena plurality of available circuit paths (two or more) to connect tooutputs of the various conductive lines in the grid. In some cases, thedigital unit 220 together with the ASIC 216 provides for alternatelyconnecting outputs of the various conductors to one of an array ofdifferential amplifiers and an array of single ended amplifiers (ordifferential amplifiers with one grounded input). In other cases, thedigital unit 220 may be operative to control triggering of one or moreconductive lines. In other examples, the ASIC 216 together with thedigital unit 220 provide for triggering various conductors with anoscillating signal having a selected pre-defined frequency orfrequencies.

The digital unit 220 may include at least a memory unit and a processingunit to store and process information obtained from the ASIC 216. Memoryand processing capability are also generally included in the host 222and the ASIC 126. According to some implementations, memory andprocessing functionality may be divided between any combination of thehost 222, the digital unit 220, and/or the ASIC 216. The pen 100,described above in FIG. 1 may communicate/interact with the digitizer200 of FIG. 2 over an electrode 160 or the tip 140. The digitizer 200may also transmit signals, for example, initiated by the host 222 or theASIC 216, to the pen 100 via the conductive lines.

FIG. 3 illustrates a pen 300 that shows portions of the pen 100 of FIG.1 and FIG. 2. The pen 300 shows portions of the pen 100, where theseportions include the TX unit 130 having a transmitter circuit 310, theRX unit 132 having a receiver circuit 330, and the electrode 160.

In one implementation, for example, the pen 300 may determine whetherthe pen 300 is to transmit information (e.g., the first information) toa digitizer (e.g., the digitizer 200 in FIG. 2) or receive information(e.g., the second information) from the digitizer. The pen 300 maydetermine whether the pen 300 is to transmit or receive informationbased on, for example, an internal state machine in a processor of thepen 300 (e.g., similar to processor 112 of pen 100). For example, if thepen 300 is to transmit the first information to the digitizer 200, theTX unit 130 which may include the transmitter circuit 330 may transmit asignal, e.g., a transmission signal, generated by the pulse generator124 and via the electrode 160. In another example, if the pen 300 is toreceive the second information from the digitizer 200, the transmittercircuit 330 may be isolated from the electrode 160, and the receivercircuit 332 may receive the second information, via the electrode 160,from the digitizer 200. The isolation of the transmitter circuit 330from the electrode 160 to enable the receiver circuit 332 to receive thesecond information from the digitizer 200 via/over the electrode 160 isbased on switching of a driver to a high impedance mode, and with a verylow parasitic capacitance, as described in detail below in reference toFIGS. 4-7.

Referring to FIG. 4, an example transmitter circuit 330 of the pen 100is illustrated.

For example, the transmitter circuit 330 may include at least a leveltranslator 412, a Schottky diode 420, a NOR gate 432, aresistor-capacitor (RC) delay circuit 440, and/or a transistor 450. Thelevel translator 412, with a low voltage input 414 and a high voltage416, may be a high-voltage push-pull level translator that drives a highvoltage signal. In this description, a high voltage signal may bereferred simply as a high signal; similarly, a low voltage signal may bereferred simply as a low signal. The output of the level translator 412is connected to an anode 422 of the Schottky diode 420 and a cathode 424of the Schottky diode 42 is connected to an output of the transmittercircuit 330. In one example, a transistor 450 may be added to thetransmitter circuit 330 to drive the output of the transmitter circuit330 low. Collector 452 of the transistor 450 may be connected to theoutput of the transmitter circuit 330, an emitter 456 of the transistor450 is connected to a Ground 458, and a base (or input) 454 of thetransistor 450 is connected an output of a buffer 434. As shown, thetransistor 450 is a bi-polar junction transistor (BJT). In otherimplementations, however, the transistor 450 can be a field-effecttransistor (FET), with the FET adding higher capacitance and/orintroducing higher leakage current.

In one implementation, the base 454 of the transistor 450 may becontrolled by an output of a logic operation, e.g., a NOR operation,with the transmission signal 410 and the control signal 430 as inputs tothe logic operation. In other words, the base 454 of the transistor 450may be controlled by the output of the logic, and the output of thetransmitter circuit 330 is pulled to the Ground 458 when the input ofthe level translator 412 is low. However, when the input of the leveltranslator 410 is high, the transistor 450 is not conductive and thetransistor 450 may not pull the output of the transmitter circuit 330.In one example, in order to have to the ability to not pull the outputof the transmitter circuit 330 output low or high (high impedance mode),a NOR gate 432 is added. The inputs of the NOR gate 432 are the input ofthe level translator 412 and a control signal 430. The control signal430 may be generated by a processor of the pen 100. In another example,when the control signal 430 is low, the NOR gate 432 may act as aninverter (as described above), and may create an inverted signal 472that controls the base 454 of the transistor 450. In a furtheradditional example, when the control signal 430 is high (e.g., a highcontrol signal or a high signal), the output 472 of the NOR gate 432 islow, and the transistor 450 is not conductive. Therefore, if the controlsignal 430 is high and the input of the level translator 412 is low, theoutput of the transmitter circuit 330 may be in high impedance mode,e.g., not pushed high by the level translator 412 and/or not pulled lowby the transistor 450. In other words, the level translator 412 byitself would not be capable of a tri-state operation (e.g., a highimpedance mode). But with the addition of the transmitter circuit 330shown in FIG. 4, a pull down (to ground) may be performed for lowvoltage levels, a pull up (to source) may be performed for high voltagelevels, and/or have a floating node or isolated node or high impedancenode.

Further, in one implementation, an additional circuit, e.g., aresistor-capacitor (RC) delay circuit 440 is added between the NOR gate432 and the transistor 450. The RC circuit 440 may be added to create a“break-before-make” logic to try to prevent a racing condition betweenpropagation delays of the level translator 412 and the NOR gate 432. Theracing condition, if not addressed properly, may cause the output of thetransmitter circuit 330 to be driven high and low, simultaneously,during 0→1 (e.g., low signal-to-high signal) or 1→0 (e.g., highsignal-to-low signal) transitions, and may lead to power waste, signaldistortion, and/or potential damage to the components of transmittercircuit 330. For example, the level translator 412 may have largerpropagation delay than the low voltage logic (e.g., NOR gate 432, RCdelay circuit 440, transistor 450, etc.). When switching between a hightransmission signal (“1”) to a low transmission signal (“0”), the inputof the level translator 412 will also switch from 1 to 0. The switchingto 0 may result in making the transistor 450 conductive very quickly andmay pull the output of the level translator 412 to the Ground 458.However, the level translator 412 which is slower may still push a highvoltage because of its large propagation delay. Therefore, a contentionscenario may occur in which the level translator 412 pushes a highvoltage and the transistor 450 pushes a low voltage. This may make thelevel translator 412 take a lot of current (e.g., enough current todamage the level translator 412), and/or produce the output signal ofthe level translator 412 with an intermediate voltage (e.g., somewherebetween a high voltage and ground voltage).

In one implementation, the RC circuit 440 may include a resistor 444 anda capacitor 446 to create an RC delay for a base signal of thetransistor 450. The introduced delay is generally larger than thepropagation delay of the level translator 412. Further, a Schottky diode442 is added in parallel to the resistor 444 in order to introduce thedelay only in a 1→0 transition of the output signal, and not introducethe delay in a 0→1 transition. This may result in the level translator412 being faster in a 1→0 transition or slower in a 0→1 transition. TheSchottky diode 442 may have a very low impedance in one direction ofcurrent (e.g., anode to cathode, 422→424), but a very high impedance inthe other direction (e.g., cathode to anode, 424→422). So in a 1→0transition, the output of the NOR gate 432 may transitions between 0and 1. The Schottky diode 442 is then in reverse voltage and has a highimpedance resulting in the RC delay. In a 0→1 transition, the output 472of the NOR 432 gate transitions between 1 and 0. The Schottky diode 442is then in forward voltage, and has very low impedance. As the Schottkydiode is in parallel to the resistor 444, their equivalent resistance isvery low, and the delay is very low (e.g., almost non-existent).However, the faster/slower transitions may be also due to the leveltranslator 412 having a larger propagation delay than the NOR gate 432.

Furthermore, in one implementation, the buffer 434 may be added betweenthe RC delay circuit 440 and the transistor 450 to put the transistor450 in saturation (for optimal conductivity). However, the seriesresistor 436 connected to the base 454 of the transistor 450 should notbe too big in order to allow sufficient current to flow to the base 454of the transistor 450. In one example, if the resistor 444 in the RCcircuit 440 is used to drive the base 454 of the transistor 450, thecapacitor 446 can be chosen such that the capacitance is large enough tointroduce the required delay. Additionally, the capacitor 446 may beconstantly charging/discharging, and may consume significant current.Therefore, the RC 440 that includes a large resistor and a smallcapacitor may be used. Further, the buffer 434 is added so that the base454 of the transistor 450 may be driven using the resistor 436 of alower resistance.

In FIG. 5, an example operation 500 of the transmitter circuit 330 isshown for driving a low voltage (e.g., low signal) on the electrode. Forexample, the transmitter circuit 330 may include a first path 502 withthe level translator 412 and other components, and a second path 504with the NOR gate 432 and other components. The transmission signal 410may be a low transmission signal, indicated by “0” (511), and providedto the level translator 412 and the NOR gate 432, and the control signal430 may be a low control signal, indicated by “0” (531), provided to theNOR gate 432. In one implementation, the output on the first path 502may be a low signal, indicated by “0” (513), and the output on thesecond path 504 may be a high signal, indicated by “1” (572). The output(572) of the second path 504 acts as an input, indicated by “1” (537) tothe base 454 of the transistor 450 which turns “ON” or enables thetransistor 450. This may result in the providing the low transmissionsignal, indicated by “0” (515) to the electrode, and driving the current“I” 539 to the Ground 458.

In FIG. 6, an example operation 600 of the transmitter circuit 330 isshown for driving a high voltage (e.g., a high signal) on the electrode.For example, the transmitter circuit may include the first path 502 withthe level translator 412 and other components, and the second path 504with the NOR gate 432 and other components. The transmission signal 410may be a high transmission signal, indicated by “1” (611), and providedto the level translator 412 and the NOR gate 432, and the control signal430 may be a high control signal or a low control, indicated by “0/1”(631), and provided to the NOR gate 432. In one implementation, theoutput on the first path 502 may be a high signal, indicated by “1”(613), and driving current “I” (619) through the Schottky diode 420 andto the electrode 160. The output on the second path 504 is a low signal,indicated by “0” (672). The output 672 of the second path 504 acts as aninput, indicated by “0” (637), to the base 454 of the transistor 450resulting in the transistor 450 being turned “OFF” or disabled.

In FIG. 7, an example operation 700 of the transmitter circuit 330 isshown for isolating the transmitter circuit 330 from the electrode. Forexample, the transmitter circuit may include the first path 502 with thelevel translator 412 and the second path 504 with the NOR gate 432. Thetransmission signal 410 may be a low transmission signal, indicated by“0” (711) and provided to the level translator 412 and the NOR gate 432,and the control signal 430 may be a high control signal, indicated by“1” (731) provided to the NOR gate 432. In one implementation, theoutput on the first path 502 may be a low signal, indicated by “0”(713), and the output on the second path 504 may be a low signal,indicated by “0” (772). The output 772 of the second path 504 acts as aninput, indicated by “0” (737), to the base 454 of the transistor 450.This may result in the transmitter circuit 330 being isolated from theelectrode 160 as there is no current path. In other words, when theoutput of the first path 502 and the second 504 are determined as lowsignals, indicated by “0”s (713 and 772), the electrode 160 is isolatedform the transmitter circuit 330, and the pen 100 may receive the secondinformation over the receiver circuit 332.

Referring to FIG. 8, an example of one implementation of a method 800performed by pen 100 for communicating or interacting with digitizer 200is described.

For example, at block 810, method 800 includes determining, at a devicehaving a transmitter circuit, a receiver circuit, and an electrode forcommunicating with the digitizer, whether the device is to transmit afirst information to the digitizer via the electrode or receive a secondinformation from the digitizer via the electrode. For example, thedevice (e.g., pen 100 of FIG. 1), based on an internal state machine inthe processor of the pen 100, may determine whether the pen 100 is totransmit a first information (e.g., transmit first information from thepen 100 to the digitizer 200) or receive a second information (e.g.,receive the second information from the digitizer 200) via the electrode160.

The pen 100 may include one or more electrodes. In one example, when thepen 100 includes one electrode, the pen 100 determines whether the pen100 is to transmit the first information to the digitizer 200 or receivethe second information from the digitizer 200 as the same electrode,e.g., electrode 160, is shared between the TX unit 130/transmittercircuit 330 and RX unit 132/receiver circuit 332. The electrode 160 maybe shared in a time division multiplexing (TDM) manner. In anotherexample, the pen 100 may contain multiple electrodes, e.g., twoelectrodes, and the pen 100 may use one electrode for transmitting andanother electrode for receiving, either simultaneously or in a TDMmanner. For instance, the pen 100 may transmit on one electrode andreceive on another electrode simultaneously if the electrode aresufficiently insulated from each other (e.g., one electrode on the tip140 and another electrode on the tail), or operating in differentfrequency bands. In a further additional example, the pen 100 may useboth the electrodes simultaneously, but both the electrodes are eitherfor transmitting or both the electrodes are for receiving if theelectrodes are sufficiently insulated from each other and/or operatingin different frequency bands.

At block 820, method 800 further includes isolating the electrode fromthe transmitter circuit in response to determining that the device is toreceive the second information from the digitizer via the electrode. Forexample, the device, e.g., pen 100, may isolate the electrode 160 fromthe transmitter circuit 330 (or the TX unit 130) in response todetermining that the device is to receive the second information fromthe digitizer 200.

Additionally, the isolating of the electrode 160 from the transmittercircuit 330 may include enabling the receiver circuit 332 of the pen 100to receive and process the second information received from thedigitizer 200 via the electrode 160.

In one implementation, the transmitter circuit 330 may receive a hightransmission signal 410 and/or a control signal 430 (the control signal430 may be a high or a low signal). The transmitter circuit 330 maytransmit a high voltage (FIG. 6) on the electrode 160 when thetransmission signal 410 is a high signal. In another implementation, thetransmitter circuit 330 may receive a low transmission signal 410 and ahigh or a low control signal 430. In one example, the transmittercircuit 330 may perform a logic operation (e.g., a NOR operation) on thelow transmission signal 410 and the high control signal 430. The outputof the logic operation may be a low signal and may result in the pen 100isolating the electrode 160 from the transmitter circuit 330 (FIG. 7).This allows the receiver circuit 332 to receive the second informationfrom the digitizer 200. In another example, the transmitter circuit 330may perform a logic operation (e.g., a NOR operation) on the lowtransmission signal 410 and the low control signal 430. The output ofthe logic operation may be a low signal and may result in the pen 100driving a low voltage on the electrode 160.

The method 800 described above provides for the TX unit 130/transmittercircuit 330 and RX unit 132/receiver circuit 332 share the electrode 160in the pen 100 for communicating/interacting with the digitizer 200.

As used in this application, the terms “component,” “system” and thelike are intended to include a computer-related entity, such as but notlimited to hardware, firmware, a combination of hardware and software,software, or software in execution. For example, a component may be, butis not limited to being, a process running on a processor, a processor,an object, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component may be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components may communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets, such as data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal.

Furthermore, various implementations are described herein in connectionwith a device, which can be a wired device or a wireless device. Suchdevices may include, but are not limited to, a gaming device or console,a laptop computer, a tablet computer, a personal digital assistant, acellular telephone, a satellite phone, a cordless telephone, a SessionInitiation Protocol (SIP) phone, a wireless local loop (WLL) station, apersonal digital assistant (PDA), a handheld device having wirelessconnection capability, a computing device, or other processing devicesconnected to a wireless modem.

Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom the context, the phrase “X employs A or B” is intended to mean anyof the natural inclusive permutations. That is, the phrase “X employs Aor B” is satisfied by any of the following instances: X employs A; Xemploys B; or X employs both A and B. In addition, the articles “a” and“an” as used in this application and the appended claims shouldgenerally be construed to mean “one or more” unless specified otherwiseor clear from the context to be directed to a singular form.

Various implementations or features will be presented in terms ofsystems that may include a number of devices, components, modules, andthe like. It is to be understood and appreciated that the varioussystems may include additional devices, components, modules, etc. and/ormay not include all of the devices, components, modules etc. discussedin connection with the figures. A combination of these approaches mayalso be used.

The various illustrative logics, logical blocks, and actions of methodsdescribed in connection with the embodiments disclosed herein may beimplemented or performed with a specially-programmed one of a generalpurpose processor, a digital signal processor (DSP), an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) or other programmable logic device, discrete gate or transistorlogic, discrete hardware components, or any combination thereof designedto perform the functions described herein. A general-purpose processormay be a microprocessor, but, in the alternative, the processor may beany conventional processor, controller, microcontroller, or statemachine. A processor may also be implemented as a combination ofcomputing devices, e.g., a combination of a DSP and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration. Additionally, at leastone processor may comprise one or more components operable to performone or more of the steps and/or actions described above.

Further, the steps and/or actions of a method or algorithm described inconnection with the implementations disclosed herein may be embodieddirectly in hardware, in a software module executed by a processor, orin a combination of the two. A software module may reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a harddisk, a removable disk, a CD-ROM, or any other form of storage mediumknown in the art. An exemplary storage medium may be coupled to theprocessor, such that the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium may be integral to the processor. Further, in someimplementations, the processor and the storage medium may reside in anASIC. Additionally, the ASIC may reside in a computer device (such as,but not limited to, a game console). In the alternative, the processorand the storage medium may reside as discrete components in a userterminal. Additionally, in some implementations, the steps and/oractions of a method or algorithm may reside as one or any combination orset of codes and/or instructions on a machine readable medium and/orcomputer readable medium, which may be incorporated into a computerprogram product.

In one or more implementations, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored or transmittedas one or more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionmay be termed a computer-readable medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs usually reproduce data optically withlasers. Combinations of the above should also be included within thescope of computer-readable media.

While implementations of the present disclosure have been described inconnection with examples thereof, it will be understood by those skilledin the art that variations and modifications of the implementationsdescribed above may be made without departing from the scope hereof.Other implementations will be apparent to those skilled in the art froma consideration of the specification or from a practice in accordancewith implementations disclosed herein.

What is claimed is:
 1. A method of communicating with a digitizer,comprising: determining, at a device having a transmitter circuit, areceiver circuit, and an electrode for communicating with the digitizer,whether the device is to transmit a first information to the digitizervia the electrode or receive a second information from the digitizer viathe electrode; and isolating the electrode from the transmitter circuitin response to determining that the device is to receive the secondinformation from the digitizer via the electrode.
 2. The method of claim1, wherein isolating the electrode from the transmitter circuit includesenabling the receiver circuit to receive and process the secondinformation received from the digitizer via the electrode.
 3. The methodof claim 1, further comprising: receiving a transmission signal and acontrol signal; and performing a logic operation based on thetransmission signal and the control signal, wherein determining whetherthe device is to transmit the first information to the digitizer via theelectrode or receive the second information from the digitizer via theelectrode is based on an output of the logic operation.
 4. The method ofclaim 3, wherein: the transmitter circuit includes a first path with alevel translator and a second path with a NOR gate, the transmissionsignal is a low transmission signal provided to the level translator andthe NOR gate, the control signal is a high control signal provided tothe NOR gate, the output of the logic operation is the output of a NORoperation performed by the NOR gate based on the low transmission signaland the high control signal, and isolating the electrode from thetransmitter circuit occurs in response to the output of the logicoperation being a low signal and an output of the level translator beinga low signal.
 5. The method of claim 4, wherein: the second path furtherincludes a delay circuit and a transistor, the method further comprisingdelaying, using the delay circuit, the output of the logical operationcarried along the second path to an input of the transistor.
 6. Themethod of claim 3, wherein: the transmitter circuit includes a firstpath with a level translator and a second path with a NOR gate, thetransmission signal is a high transmission signal provided to the leveltranslator and the NOR gate, the control signal is a high control signalor a low control signal provided to the NOR gate, the output of thelogic operation is the output of a NOR operation performed by the NORgate based on the high transmission signal and the control signal, andproviding the high transmission signal to the electrode in response tothe output of the logic operation being a low signal, and the hightransmission signal being level shifted by the level translator.
 7. Themethod of claim 6, further comprising: driving a current via thetransmitting circuit and the electrode for communicating with thedigitizer.
 8. The method of claim 3, wherein: the transmitter circuitincludes a first path with a level translator and a second path with aNOR gate, the transmission signal is a low transmission signal providedto the level translator and the NOR gate, the control signal is a lowcontrol signal provided to the NOR gate, the output of the logicoperation is the output of a NOR operation performed by the NOR gatebased on the low transmission signal and the low control signal, andproviding the low transmission signal to the electrode in response tothe output of the logic operation being a high signal, and the lowtransmission signal being level shifted or passed through by the leveltranslator.
 9. The method of claim 1, further comprising: controllingthe transmitter circuit and the receiver circuit for communicating withthe digitizer over the electrode using time division multiplexing (TDM).10. The method of claim 1, wherein the device is a stylus.
 11. A devicefor communicating with a digitizer, comprising: a transmitter circuit; areceiver circuit; an electrode for communicating with the digitizer; amemory; and a processor in communication with the memory, wherein theprocessor is configured to: determine whether the device is to transmita first information to the digitizer via the electrode or receive asecond information from the digitizer via the electrode; and isolate theelectrode from the transmitter circuit in response to determining thatthe device is to receive the second information from the digitizer viathe electrode.
 12. The device of claim 11, wherein isolation of theelectrode from the transmitter circuit includes enabling the receivercircuit to receive and process the second information received from thedigitizer via the electrode.
 13. The device of claim 11, wherein thetransmitter circuit is further configured to: receive a transmissionsignal from a pulse generator and a control signal from the processor;and perform a logic operation based on the transmission signal and thecontrol signal, wherein the processor is further configured to generatethe control signal based on whether the device is to transmit the firstinformation to the digitizer via the electrode or receive the secondinformation from the digitizer via the electrode.
 14. The device ofclaim 13, wherein: the transmitter circuit includes a first path with alevel translator and a second path with a NOR gate, the transmissionsignal is a low transmission signal provided to the level translator andthe NOR gate, the control signal is a high control signal provided tothe NOR gate, the output of the logic operation is the output of a NORoperation performed by the NOR gate based on the low transmission signaland the high control signal, and wherein the processor is furtherconfigured to isolate the electrode from the transmitter circuit bygenerating the high control signal in response to determining that thedevice is to receive the second information from the digitizer.
 15. Thedevice of claim 14, wherein the second path further includes a delaycircuit to delay the output of the logical operation carried along thesecond path to an input of a transistor.
 16. The device of claim 14,wherein: the transmitter circuit includes a first path with a leveltranslator and a second path with a NOR gate, the transmission signal isa high transmission signal provided to the level translator and the NORgate, the control signal is a high or a low control signal provided tothe NOR gate, wherein the transmitter circuit is further configured totransmit a high voltage on the electrode in response to determining thatthe device is to transmit the first information to the digitizer. 17.The device of claim 14, wherein: the transmitter circuit includes afirst path with a level translator and a second path with a NOR gate,the transmission signal is a low transmission signal provided to thelevel translator and the NOR gate, the control signal is a low controlsignal provided to the NOR gate, the output of the logic operation isthe output of a NOR operation performed by the NOR gate based on the lowtransmission signal and the low control signal, and wherein theprocessor is further configured to provide the low transmission signalto the electrode in response to the output of the logic operation beinga high signal, and the low transmission signal being level shifted orpassed through by the level translator.
 18. The device of claim 11,wherein the processor is further configured to: control the transmittercircuit and the receiver circuit for communicating with the digitizerover the electrode using time division multiplexing (TDM).
 19. Thedevice of claim 12, wherein the device is a stylus.
 20. Acomputer-readable medium storing computer-executable instructionsexecutable by a processor for communicating with a digitizer,comprising: instructions for determining, by a device having atransmitter circuit, a receiver circuit, and an electrode forcommunicating with the digitizer, whether the device is to transmit afirst information to the digitizer via the electrode or receive a secondinformation from the digitizer via the electrode; and instructions forisolating the electrode from the transmitter circuit in response todetermining that the device is to receive the second information fromthe digitizer via the electrode.